The present invention relates to an elevator control system.
A recent technical trend of the elevator control system shifts from the control using mechanical components to that using electric and electronic components due to various factors; development of electronics, lengthened travelling length of elevator cars, speed-up of elevator travelling, high-level demands of passengers, and the like.
In elevator control systems, a basic operation is that, when a call is registered, a car moves in response to the registered call to satisfy the demand of the call. In order to improve the service, however, consideration is taken so that, even after the car starts to move, it answers to the call issued from the floor at which it is permitted to stop for service. For this, the elevator control must calculate the position or floor at which the travelling car may stop in relation to its travelling speed, by some method. In conventional control systems with mechanical type floor selectors, the car stop is decided by using a selector (to indicate the car position) moving synchronized to travel of the car and an advance selector (to indicate the position permitting the car to stop thereat) moving proportional to travel of the car. However, the mechanical type control system can hardly exert its proper control to high-speed and high-rise elevator systems, due to the limitation of finishing accuracy, diminishing scale, and the like. This has contrived the electric type floor selector.
FIG. 1 shows an elevator control system employing the electric type floor selector. In the figure, (1) is an elevator car which is supported by a hoisting rope (4) extending up over a traction sheave (3) provided around the shaft of a drive motor (2). (5) is a counterweight connected to the other end of the rope (4). (6) is a looped speed governor rope connected at one end to the top of the car (1) while at the other end to the bottom of the car (1). The speed governor rope is wound around a governor sheave (7) disposed over the top of the car (1) running in the hoistway and a pulley (8) disposed at the bottom of the hoistway. (9) is a pulse generator for pulses corresponding to the amount of the travel of the car (1) coupled with the governor sheave (7), and generates one pulse each unitary movement (for example, 5 mm, 10 mm) of the cage (1). (10) designates respective floors and 1st to nth floors represented by (1F) to (nF). (11) designates a device indicating the levelling zone. Each floor is provided with one identical device of the levelling zone indication. A detecting device (12) provided on the car (1) permits one to know that the car (1) enters the levelling zone. (13) designates an electric type floor selector. (13a) is a car position arithmatic unit which counts the number of pulses fed from the pulse generator (9) when the car (1) goes up, with a reference floor of the floor (1F). Through the counting operation, it indicates the position in the hoistway where the car (1) passes with respect to the reference point (1F). (13b) denotes a floor position memory for permanently memorize the positions of respective floors in terms of the distance from the reference point. (1F). By addressing one of the floors (1F) to (nF), it produces the distance from the reference point corresponding to the floor addressed.
(13c) is a stop permissible position arithmatic device in which the stop permissible position of the running car (1) is calculated on the basis of the position information fed from the pulse generator (9), the speed information (not shown) of the car (1) and like. (13d) is a comparator in which the output of the floor position memory (13b) and the output of the stop permissible position arithmatic unit (13c) are compared to produce a large or small magnitude output of a result of the comparison in accordance with the travelling direction of the car (1). (13e) is a stop permissible floor indicator which increases or decreases by one each time the output of the comparator (13d) is given thereto to produce an output indicating the stop permissible floor. (13f) represents a stop decision arithmatic unit which receives at the input a call corresponding to the stop permissible floor fed from the stop permissible floor indicator (13e) and produces a stop decision signal when there is a responsible call. (13g) represents a remaining distance arithmatic unit in which, when the stop of the car (1) is decided, a difference is calculated between the distance of the stop decided floor from the reference point and the distance of the car (1) positioning at present from the reference point to produce the remaining distance by which the car (1) must travel till it stops which in turn is applied to a speed pattern generator 8 (not shown).
Assume now that the car (1) stops at the floor (1F) (used as the reference floor), and at this time the car position (13a) is zero and the stop permissible floor indicator (13e) indicates (1F). Under this condition, the car (1) starts to move in response to generation of a call from an upper floor. With movement of the car (1), the speed governor sheave (7) starts to rotate and the pulse generator (9) generates the number of pulses corresponding to the amount of the car (1) movement. The pulses are fed to the car position arithmatic unit (13a) and the stop permissible position arithmatic unit (13c) where necessary calculation are performed. The stop permissible floor indicator (13e) indicates (2F) to which 1 is automatically added by an up-direction start signal (not shown) of the car (1). The floor position memory (13b) outputs the distance from the reference point to the floor (2F), with addressing (2F). The comparator (13d) compares the output of the floor position memory (13b) with (2F) addressing with the output of the stop permissible position arithmatic unit (13c ). When the output of the stop permissible position arithmatic unit (13c) is larger, the comparator (13d) produces a large signal which adds 1 to the contents of the stop permissible floor indicator (13e). With the addition of 1, the indicator produces (3F) while the floor position memory (13b) produces an output with addressing of (3F). In this manner, the output of the stop permissible floor indicator (13e) changes. On the other hand, the stop decision arithmatic unit (13f) constantly seeks a call to be responsed to the stop floor indicated by the stop permissible indicator (13e). If a call is now generated from the floor (4F), the stop decision arithmatic unit (13f) issues a stop decision signal to be directed to the stop permissible position arithmatic unit (13c) thereby to stop the operation of it. After this, the comparator (13d) does not operate and the output of the stop permissible floor indicator (13e) indicates the floor at which the car (1) will stop. Further, the stop decision signal is given to the remaining distance arithmetic unit (13g) which in turn produces the difference between the position of the car (1) in the hoistway and the position by the floor position memory (13b), as the remaining distance to be travelled by the car (1).
When the levelling zone indicating device (11) and the detecting device (12) cooperate to detect that the car enters the levelling zone, a levelling device (not shown) separately provided generally causes the car (1) to be levelled with the floor level to stop its travelling. Upon the stop of the car (1), the output of the floor position memory (13b) with the stop floor address of the output of the stop permissible floor indicator (13e) is applied to the car position arithmetic unit (13a) and the stop permissible position arithmetic unit (13c) to set up the initial condition of the car position arithmetic unit (13a) and the stop permissible position arithmetic unit (13c). In response to a new call, calculation is performed on the basis of the initial condition and the stop is repeated in response to the call.
No problem arises as far as respective apparatuses and units operate correctly; however, when slip takes place, for example, between the speed governor rope (6) and the speed governor sheave (7) and the amount of the slippage exceeds one floor, the floor at which the car actually stops is not coincident with the stop floor indicated by the stop permissible floor indicator (13e), resulting in trouble of elevator service. One of the countermeasures for this is that, as shown in FIG. 2, floor identifying units (14-1F) to (14-nF) each for identifying the corresponding floor are installed at the floors, respectively, and a stop floor identifying indicator (13h) receiving as its input the output of a floor name detecting unit (15) attached to the car (1) and the stop permissible indicator (13e) are corrected each time the car (1) stops.
In this attempt, each floor needs the floor identifying units (14-1F) to (14-nF) for indicating the name of the corresponding floor. Accordingly, when the number of the floors is large, manufacturing of individual floor identifying units and fitting thereof cost much labor and the floor name detecting unit (15) is complex in construction, thus being disadvantageous from economical view point.